Summary

• Most common symptoms and signs are dyspnoea and hypoxaemia, which progress to acute respiratory failure.
• Common causes are pneumonia, sepsis, aspiration, and severe trauma.
• Diagnostic criteria are acute onset (<1 week), bilateral opacities on CXR, hypoxaemia with PaO2/inspired oxygen ratio ≤300 on PEEP or CPAP ≥5 cm H2O. In patients with no risk factor for ARDS, heart failure should be ruled out.
• Mortality is between 30% and 50%.
• Low tidal volume, plateau-pressure-limited mechanical ventilation is the only therapy that has been shown to reduce mortality.
• Complications include pneumothorax, ventilator-associated pneumonia, multiple organ failure, and pulmonary fibrosis with prolonged respiratory failure.